The Einstein Toolkit is one of the oldest open-source, freely-accessible, community-driven code frameworks for studying fully general relativistic systems such as black holes, neutron stars, and supernovae. The toolkit was developed by an international collaboration of students and professors working at many institutions. The toolkit is built in layers, offering generic computational infrastructure components at its lowest level—e.g., adaptive mesh refinement, method of lines, and I/O—and base modules which provide commonly-defined variables for an evolution system at a higher level. The base level provides a communication interface for more specific spacetime formulations, hydrodynamical schemes, and analysis tools like horizon finders, gravitational wave extractors, ejecta trackers, and others.